Brake system master-cylinder seal

Abstract

Master-cylinder seal housed in a groove around a piston has a core connected to three annular and concentric lips. The core rests against a side of the groove and has: a surface provided with an interior edge followed by a peripheral platter cut by at least one channel, and an exterior crown provided with a connection zone formed by an interruption in the crown and deformable due to pressure within the seal to recreate the crown's continuity and impermeability while facilitating purging the brake system when there is no pressure in the channel and the connection zone.

The invention claimed is:  
     
       1. A substantially annular-shaped seal for being housed in a groove of a body of a brake system master cylinder and around a piston, the seal comprising:
 a core section; and 
 three substantially annular and concentric lips including an interior lip, an intermediate lip, and an exterior lip; 
 wherein:
 the three lips each includes a free end and a connection end connected with the core section, at least one portion of the free end of the intermediate lip extending axially beyond the free ends of the interior and exterior lips; 
 the connection ends are axially closer to a base surface of the core section than the free ends; 
 a periphery of the intermediate lip is interrupted so as to include multiple circumferentially-spaced portions; 
 the base surface of the core section includes:
 a peripheral platter that includes at least a first section, and a second section that is radially exterior to the first section, and a third section that is radially exterior to the second section; 
 a raised exterior crown that (a) is radially exterior to the first section of the peripheral platter, (b) is radially interior to the third section, and (c) includes a plurality of sections raised axially beyond the peripheral platter in a direction away from the free ends of the lips and circumferentially separated by at least one connection zone that is formed by the second section of the peripheral platter; and 
 at least one channel formed in the peripheral platter, extending radially outward in a direction from an interior edge of the seal, and terminating radially before the connection zone; and 
 
 the third section of the peripheral platter forms at least one heel each of which is radially in line with a respective one of the at least one connection zone. 
 
 
     
     
       2. The seal according to  claim 1 , wherein, with respect to a radially outward direction, the channel terminates substantially at a radial coordinate at which the exterior crown begins. 
     
     
       3. The seal according to  claim 1 , wherein the seal is of a flexible material such that, if, while the raised exterior crown is pressed in an axial direction against a wall of the groove, a pressure force is applied against the seal in an axial direction towards the wall of the groove, the at least one connection zone would be deformed axially closer to an exterior surface of the raised exterior crown. 
     
     
       4. The seal according to  claim 1 , wherein the heel is a radial protrusion circumferentially bordered by recessed sections of the base surface beyond which the heel is raised axially in the direction away from the free ends of the lips. 
     
     
       5. A brake system master cylinder, comprising:
 a body having a pressure chamber which receives a piston, wherein the pressure chamber has a bore hole, the bore hole including a groove which separates the pressure chamber from a supply chamber connected to a hydraulic fluid supply chamber; and 
 a seal element providing a seal for the piston in the body of the master cylinder; 
 wherein
 the seal element is received in the groove; 
 the seal element is substantially annular-shaped and includes a core section and three substantially annular and concentric lips including an interior lip, an intermediate lip, and an exterior lip; 
 the three lips each includes a free end and a connection end connected with the core section, at least one portion of the free end of the intermediate lip extending axially beyond the free ends of the interior and exterior lips; 
 the body of the master cylinder includes a first wall against which a surface of the core section rests; 
 a periphery of the intermediate lip is interrupted so as to include multiple circumferentially-spaced portions forming supports and passages with a second wall of the body of the master cylinder opposite the first wall; 
 the surface of the core section includes:
 a peripheral platter that includes at least a first section, a second section that is radially exterior to the first section, and a third section that is radially exterior to the second section; 
 a raised exterior crown that (a) is a radially exterior to the first section of the peripheral platter, (b) is radially interior to the third section, and (c) includes a plurality of sections raised axially beyond the peripheral platter in a direction away from the free ends of the lips and circumferentially separated by at least one connection zone that is formed by the second section of the peripheral platter; and 
 at least one channel formed in the peripheral platter, extending radially outward in a direction from an interior edge of the seal, and terminating radially before the connection zone; and 
 
 the third section of the peripheral platter forms at least one heel, each of which is radially in line with a respective one of the at least one connection zone. 
 
 
     
     
       6. The brake system master cylinder according to  claim 5 , wherein the master cylinder is (i) a simple master cylinder with a single piston and the groove receiving the seal element, or (ii) a tandem master cylinder with a principal piston and an auxiliary piston, each of which pistons cooperates with the seal element received in the groove of the body of the master cylinder.